Friday, November 7, 2014

Model Profile, Centuri Aerobee 350

Here's one I found on my bedroom shelf on the recent California trip - the Centuri Aerobee 350.
The kit was ST-10 based and stood 16 1/2" tall.

You can see this original catalog page HERE
I searched online and couldn't find the instructions anywhere.

Kit parts and construction tell us this was an earlier run of the kit.
The shock cord mount was laced through cut slits in the body tube.

The 1972 catalog description mentions a "Payload Section" nose cone. That suggests a newer snap on base plastic nose cone.
The balsa cone shoulder is only about 5/16" long!
The red shroud lines are tied onto the screw eye.

This one was built at around 1975. I got a pretty good airfoil on the fins. One fin was broken off.
The inset picture shows bubbles in the launch lug fillet. Titebond M&TG wasn't on the market yet.
The body tube shows some body tube seams. Back then I wasn't filling them in. The balsa grain isn't showing. I used four coats of sanding sealer, sanding between coats.
The rocket was clean, never flown.

I don't know why the conduit tunnels were left off. They are shown in the catalog pictures.
This sure doesn't look like the catalog color scheme.


  1. Chris she looks perfect for 1975. Did you use primer or just straight gloss enamel paint? 4 coats of balsa sealer before or after gluing fins on? I follow your blog and see how you currently finish and build your rockets. What was your typical building and finish schedule like in 1975?

    1. Hi David,
      I wasn't using primer back then, just four coats of sanding sealer and sanding between coats.
      I was filling the fins before gluing them onto the body tube. Now I use Carpenter's Wood Filler on fins and being water based the fin and body tube glue bond would be stronger than the sealed balsa.
      Krylon spray paint was used back then. It looks a little translucent. The mask on the body tube was done with Rubylithe. That's a photo mask film used in print shops, probably not available now.
      When this model was built my finish schedule was:
      4 coats of sanding sealer, sanding between coats.
      I didn't use an white undercoat then.
      Light colors sprayed first, light sanding between coats.
      Masking and the second color coat.

      That's about it - decals would be applied but there was no Future or clear coats.

  2. Chris,
    Once again your builds are awesome. Your current build methods produce nothing short of catalog quality rockets. I really enjoy the pictures of the rockets you built back in the 70s, they look great for what you had back in the day. If you ever want to sell one of those old rockets just give me a shout. I am amazed how well your rockets look when you were not using primers or fillers to fix problem areas, only proves you are meticulous builder that can build a perfect rocket even before the finish goes on. What is the time comparison of building a rocket back then compared to your new techniques? I think one issue today is using Enamels delay the process. The old Krylon could be sanded within a few hours and recoated anytime and today paints take 24 hours to dry and 48 to 72 hours to recoat. Once again, keep the old rocket pictures coming they are nice trip down memory lane. As you have seen on the forums I have been trying to match your old style of building techniques with my last couple of build, even a OOP Centuri Astro.

    1. Hi David,
      Thanks for the compliments.
      That older Aerobee isn't for sale but occasionally I sell finished models on Ebay and do custom builds for clients, all the way up to the Estes Saturn V.
      The best way to improve finishes are to have good surface prep and sanding between finish coats.
      In some ways, building is easier now. One coat of Carpenter's Wood Finish is faster than four coats of sanding sealer.
      The old Krylon did dry faster than the Rusto 2X I use now.
      The Tung wood in the Estes kits is harder and a little heavier than the old balsa. Tung wood seems harder to fill and finish.
      I probably spend less time on a build now. I have better tools and have learned from years of fixing mistakes.
      I wish I had more pictures of older builds but the models have disappeared over the years.

  3. Chris,
    Thanks for taking the time to respond to my questions, sometimes I like the old way things were done. Anyway here a link to the masking film you used.

    1. Hi David,
      That's the stuff! I haven't seen it for years.
      Over the past few years I've had great results using Scotch tape for masks and probably wouldn't go back to using the Rubylith.
      On a visit to Centuri I mentioned I'd used Rubylith masks. They said they had used it too!

  4. I have never heard of the Rubylith masks before, but I also have good luck with Scotch tape. How come primer was not used back in the day? I take the builders at Centuri and Estes didn't use primer either. Couple of more questions, so back in the day you brush on 4 coats of Aerogloss Balsa sealer not the filler with sanding in between each coat, 320 or 400 grit? No matter how well I fill the balsa there is sometimes a spot or two that even the primer does not fill so I have to brush on some wood filler. What did you use back in the 70s when you had a spot where the grain was still showing?

    1. Hi David,
      I wouldn't use the Rubylith now, I think the Scotch tape has a stronger tack. Back then I was trying a lot of things to get a better mask. We didn't have specialty tapes, just brown masking tape.
      Understand that Rubylith wasn't meant to be a masking tape, but used for color separations in a black and white print shop camera.
      I didn't use primer back then, I didn't know it existed. I wasn't around auto body shops to see it used.
      I used 400 grit to sand down sanding sealer.
      To fill remaining balsa grain after the first shot of white undercoat, I used some lightweight white wall spackle. It easily sanded flush with the surface and being white, blended in pretty well.
      Sometimes you have a rough spot but the grain is still filled. You can lightly sand over the rough area in between color coats. By the time the last coat goes on the rough area should be smoothed over.

  5. Chris,
    Here are some of my recent builds using old school techniques and I am happy with the results. My next build I will use old formula Krylon and I'll let you know how that goes. I wonder if the old Estes and Centuri catalog rockets had spirals and grain showing? I was reading some of your older blogs and I was laughing at the fact Centuri used Titebond glue to fill their little bottles. I wonder if Centuri used Aerogloss sealer and filler for their brand of filler and sealer.

    1. Hi David,
      So your are Scigs30. Great job on the builds!
      I was lucky enough to see some of the Estes and Centuri catalog models up close. There were tube spirals and balsa grain on some. Those catalog pictures were airbrushed to hide the spirals and smooth things out.
      I wouldn't doubt it if Centuri re-labeled other products too.